Matrix assembly with segmented matrices

ABSTRACT

This disclosure relates to a matrix assembly for treading tires and includes a pair of matrix shell halves each of which has mounted therein segments which combine to define one half of a matrix. The matrix segments are resiliently urged out of the matrix shell in guided relation so that when the matrix assembly is open for the reception or discharge of a tire, the matrix segments are expanded so as to facilitate the loading and unloading of the matrix. A principal feature is the provision of wear retarding means whereby the matrix segments, which are normally formed of a relatively soft metal, such as aluminum, are not unduly worn as they shift relative to the shell halves.

[ MATRIX ASSEMBLY WITH SEGMENTED MATRICES Kenneth T. MacMillan, 4992Wesleyan Woods Dr., Macon, Ga. 31202 Filed: Apr. 11, 1972 Appl. No.:243,366

Related U.S. Application Data Continuation-impart of Ser. No. 90,687,Nov. 18, 1970, abandoned.

Inventor:

US. Cl 425/20, 425/25, 425/47, 425/DIG. 5, 249/205, 308/4 R, 92/171 Int.Cl 132% 5/04 Field of Search 425/23, 25, 28, 29, 425/38, 40, 47, DIG. 5;249/68, 205; 308/4 I M w "x" it I 1 Dec. 11, 1973 3,724,981 4/1973Schiemann 425/DlG. 5 2,272,718 2/1942 MacLagan et a1. 249/68 UX3,044,120 7/1962 Wiskoff et a1. 249/68 2,969,569 1/1961 Brown 249/68FOREIGN PATENTS OR APPLICATIONS 1,160,606 1/1964 Germany PrimaryExaminerJ. Howard Flint, Jr. AttorneyCharles E. Brown et al.

[57] ABSTRACT This disclosure relates to a matrix assembly for treadingtires and includes a pair of matrix shell halves each of which hasmounted therein segments which combine to define one half of a matrix.The matrix segments are resiliently urged out of the matrix shell inguided relation so that when the matrix assembly is open for thereception or discharge of a tire, the matrix segments are expanded so asto facilitate the loading and unloading of the matrix. A principalfeature is the provision of wear retarding means whereby the matrixsegments, which are normally formed of a relatively soft metal, such asaluminum, are not unduly worn as they shift relative to the shellhalves.

6 Claims, 3 Drawing Figures MATRIX ASSEMBLY WITH SEGMENTED MATRICES Thisapplication is a eontinuation-in-part of my copending application Ser.No. 90,687, entitled MA- TRIX, filed Nov. 18, 1970, now abandoned.

This invention relates in general to new and useful improvements inmatrix assemblies for treading tires.

BACKGROUND OF THE INVENTION It is well known to form a tire treadingmatrix in segments and to associate the segments with a holder wherebyonce a tire is placed within the matrix segments, the holder may bemoved to a matrix clamping position with the matrix closingcircumferentially and radially inwardly about the tire preparatory tothe curing of the tire tread. Such a matrix construction is found in thepatent to Donald MacMillan US. Pat. No. 3,520,025, granted July l4,1970. It is also known from German patent specification No. 1,160,606dated Jan. 2, 1964, for the mold segments to be mounted on guide pinscarried by the matrix shell halves with the guide pins being disposed atan angle to the general axis of the matrix assembly, and for the matrixsegments to be spring loaded to move axially relative to the shellhalves whereby when the matrix assembly is opened, the matrix segmentsautomatically move axially and circumferentially to open positions forthe reception or release of a tire. 7

It will be readily apparent that in order for the matrix segments tocooperate with one another to form the desired matrix halves, it isnecessary that the matrix segments be accurately positioned by the shellhalves in the closed position of the matrix assembly. However, it hasbeen found that the relative sliding movement of the matrix segmentswith respect to the shell halves has resulted in the wearing ofcomponents, particularly when the matrix segments are formed of arelatively soft metal, such as aluminum, and therefore, while the matrixassemblies have performed satisfactorily when new, after they have beenused for a limited period of time, they have worn to the extent thatthey do not perform satisfactorily.

SUMMARY OF THE INVENTION In accordance with this invention, it isproposed to provide a matrixx assembly of the foregoing type but whereinwear retarding means are provided for retarding wearing of the matrixsegments during the movement of the matrix segments between open andclosed positions.

It is to be understood that in the open position of the matrix segments,the matrix segments are circumferentially spaced. Thus, as the matrixsegments move to a closed position, the matrix segments not only moveaxially, but also circumferentially. In the closed position of thematrix segments, the matrix segments are seated on a generallycircumferential, but sloping surface of the shell halves with thecooperation being a wedging cooperation and the matrix segments beingtightly wedged together by such cooperation.

In the past, there has been sliding contact between the outer peripheryof the matrix segments and the inner periphery of the shell halves.However, an attempt has been made to control this sliding engagement bymounting the matrix segments on guide pins. The guide pins, however,merely define the path of movement of the matrix segments and do notprevent the sliding frictional engagementbetween the matrix segments andthe shell halves.

In accordance with this invention, it is proposed to mount the guidepins at a lesser angle to the axis of the matrix assembly than themating peripheral surfaces whereby as the matrix segments move fromtheir seated or closed positions, they are moved circumferentiallyinwardly out of contact with the shell halves, thus eliminating thisundesirable frictional engagement.

Another feature of the invention is to provide the outer peripheralsurface of the matrix segments with a hardened surface which isresistant to wear so that any sliding contact thereof with the shellhalves will not unduly result in the wearing of the matrix segments.

Another feature of the invention is the proper mounting of the matrixsegments on the guide pins for guided sliding movement. This isaccomplished by providing the matrix segments with hardened insertswhich are constructed to cooperate with the guide pins so as to assurethe proper guiding of the matrix segments. At the same time, because theinserts are hardened, there is no appreciable wear which would limit theguiding ability of the guide pins.

With the above and other objects in view that will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawings:

IN THE DRAWINGS FIG. 1 is a plan view of one half of the matrix assemblyshowing the half in its open condition.

FIG. 2 is an enlarged fragmentary vertical sectional view takengenerally along the line 2-2 of FIG. 1 and schematically illustrates atire to be tread positioned within the matrix half.

FIG. 3 is a sectional view similar toFIG. 2 but shows the matrixassembly in its closed position with the matrix segments being seated inthe shell half, there also being shown a portion of the upper half ofthe matrix assembly in phantom lines.

Referring now to the drawings in detail, it will be seen that there isillustrated the matrix assembly which is the subject of this invention,the matrix assembly being generally identified by the numeral 10. Thematrix assembly 10 includes an upper matrix shell half 11 (FIG. 3) and alower matrix shell half 12. The remote ends of the shell halves 11,12are provided with flanges 13 to facilitate the gripping thereof within amatrix loader (not shown). Thus, when the matrix assembly 10 is placedwithin a matrix loader, the matrix shell halves 11,12 may be readilygripped and the matrix assembly 10 divided into two halves through theopening thereof by means of the matrix loader.

The matrix shell halves 11,12 have mating faces 14 in contactingrelation when the matrix assembly 10 is closed, one of the matrix shell.halves being provided with a projection 15 adjacent the mating face 14thereof and the other of the matrix shell halves being provided with alike annular projection 16. With particular reference to FIG. 3, it willbe seen that when the matrix shell halves 11,12 are brought togetherwith their mating surfaces 14 in contacting relation, the matrixassembly 10 may be clamped in a closed position by means of a peripheralclamping ring (not shown) which may engage the projections 15,16. Theclamping ring may be of any conventional construction and thedescription thereof here is believed to be unnecessary.

Referring now to FIG. 1 in particular, it will be seen that the matrixshell half 12 is provided with a plurality of matrix segments 20. In theillustrated form of the matrix assembly, each matrix shell half isprovided with four matrix segments 20. However, the number of matrixsegments may vary although normally three is considered to be a minimumnumber and four to be a practical number of matrix segments for eachmatrix shell half.

Each of the matrix segments is carried by a pair of guide pins 21 whichare of a special construction. Each guide pin 21 includes an enlargedhead 22 which is preferably circular in cross section, a stem portion 23and a reduced cross sectional threaded end portion 24. Because thematrix shell halves 11,12 are normally formed of a relatively soft metalhaving good heat conducting characteristics, such as aluminum, thematrix shell halves are preferably provided with inserts 25 which arereplaceable and which have threaded bores 26 receiving the threaded ends24 of the guide pins 21. Furthermore, an oversized washer 27 is clampedbetween the stem portion 23 and the insert 25.

Inasmuch as the guide pins 21 are fixed and the ma trix segments 20 aremounted for movement relative to the guide pins 21, and since the matrixsegments 20 are preferably formed of a relatively soft heat conductingmetal, such as aluminum, wear between the contacting guide parts willmost likely occur. In order to prevent this, each matrix segment 20 isprovided with a guide insert 28 for each of the guide pins 21. Eachinsert 28 is replaceably seated in a socket 30 which is an enlargementof a lower socket 31 in which the stern portion 23 is freely positioned.The insert 28 includes a tubular body 32 defining an internal guidesurface 33 which cooperates with a head 22 of the guide pin 21. Theinsert 28 also includes a base or bottom wall 34 having an aperture 35therethrough snugly engaging the stem portion 23 and forming a guidesurface therefor.

From the foregoing, it will be readily apparent that the relationshipbetween the guide pins 21 and the inserts 28 is such that each matrixsegment 20 is guided for movement along a predetermined path and at thesame time, the contacting components are of a construction which resistswearing thereof so that the accuracy of movement of the matrix sections20 is maintained over a period of time.

In order that the matrix segments 20 may automatically be moved to openpositions, each guide pin 21 has associated therewith a compressionspring 36 which is telescoped over the lower portion of the respectiveguide pin 21 and which has the opposite ends thereof contacting thewasher 27 and the underside of the base 34. Inasmuch as the compressionspring 36 engages only relatively hard materials, no undue wearingaction results.

With particular reference to FIG. 2, it will be seen that the matrixshell half 12 is provided with a seating surface 40 which lies generallyin a plane disposed transversely of the axis of the matrix assembly. Ina like manner, each matrix segment 20 is provided with a seating surface41 which opposes the seating surface 40 and is cooperatively engageabletherewith to position the mold segments 20, as is shown in FIG. 3.

The shell halves 11,12 are also provided with a generallycircumferential seating surface 42 which slopes towards the axis of thematrix assembly. The outer peripheral of each mold segment 20 includes aseating surface 43 which corresponds generally thereto and is cooperabletherewith in the manner shown in FIG. 3 to serve in urging the matrixsegments 20 radially inwardly. It will be readily apparent that as themold segments 20 move between open and closed positions, there isrubbing contact between the surfaces 42,43. To prevent undue wearing ofthe relatively soft metal, the mold segments 20 are provided with wearresisting jackets 44 which are preferably formed of a special aluminumalloy.

It is to be noted that the seating surface 42 is disposed at an angle Xto the axis of the matrix assembly. It is also to be noted that taken ina plane normal to the plane containing the two guide pins 21 of aselected matrix segment 20, the angle between the axis of the guide pin21 and the axis of the matrix assembly is identified as angle Y. Angle Xis greater than angle Y, for example, angle X may be 20 while angle Y is18. Thus, when a matrix segment 20 moves away from its respective seat40, it moves both axially and circumferentially. However, the extent ofthe circumferential movement of the matrix segment 20 is less than theangle of slope of the seating surface 42 with the result that themovement of the matrix segment 20 relative to the seating surface 42 isboth axially and circumferentially inwardly. Thus, as the matrix segment20 moves away from the seating surface 40, the seating surface 43thereof moves away from the seating surface 42. In this manner, therubbing engagement between seating surfaces is restricted to that whichoccurs during an initial opening movement and during a final closingmovement.

It will be readily apparent that the various wear retarding meanscombine to define an assembly wherein repeated relative movement betweenthe matrix segmentsand matrix shell halves may occur without unduewearing of the parts thereof. Inasmuch as the parts are subject to weareach time the matrix assembly is open and each time it is closed, itwill be readily apparent that this wear could be very severe.

The matrix assembly will, of course, be provided with some suitable typeof heating means. In FIGS. 2 and 3 the heating means has beenillustrated as being a conventional electrical heating element 45 whichis embedded in the matrix shell halves.

In the operation of the matrix assembly 10, when the matrix shell halves11,12 are moved apart, the springs 36 will automatically operate to urgethe matrix segments 20 out of their seated positions with respect to theshell halves 11,12, as is shown in FIG. 3. When the matrix segments 20are in this open position, a tire 47, which is to be cured, may bereadily positioned within the matrix assembly. Then as the shell halves11,12 are brought together, the matrix segments 20 will move togetherand towards the shell halves to the fully seated position of FIG. 3 atwhich time tread molding surfaces 48 thereof will come into pressurizedcontact with the tube portion which is to be molded and the desiredtread will be molded within the tire in the manner shown in FIG. 3.

Once the tire has been properly treaded and cured, and the matrixassembly 10 is again opened, the matrix segments 20 will automaticallymove apart and separate themselves from the tire which has just beenretreaded, generally as is shown in FIG. 2.

Although only a preferred embodiment of the invention has beenspecifically illustrated and described herein, it is to be understoodthat various minor modifications may be made in the matrix constructionwithout departing from the spirit and scope of the invention, as definedby the appended claims.

I claim:

1. A matrix assembly for use in treading tires, said matrix assemblycomprising cooperating axially separable matrix shell halves, a matrixhalf carried by each matrix shell half, said matrix assembly having anaxis about which said matrix shell halves and said matrix halves aregenerally centered, each matrix half and its respective matrix shellhalf having first cooperating seating surfaces engageable in a planeextending generally transverse to said axis and second cooperatingseating surfaces extending generally circumferentially around said axisand disposed at a converging angle to said axis, each matrix half beingformed of a plurality of segments separately movable within and relativeto the respective matrix shell half in a combined axial andcircumferential direction from its seated position to a matrix expandingposition for the release of a treaded tire and the reception of a tireto be treaded, a pair of guide pins carried by each matrix shell halfmounting each respective matrix segment for guided retained movementbetween said seated position and said matrix expanding position, saidmatrix segments being formed of a relatively soft heat conducting metal,and wear retarding means for retarding wearing of said matrix segmentsduring the movement of said matrix segments, said wear retarding meansincluding said guide pins of each matrix segment being parallel andlying in a plane disposed at an angle to said axis generally equal tobut slightly less than said angle of said second seating surfaceswhereby as said matrix segments move to sepa rate said first seatingsurfaces said matrix segment second seating surfaces movecircumferentially inwardly away from the respective matrix shell halfsecond seating surface and thereby prevent wearing of said secondseating surfaces.

2. The matrix assembly of claim 1 wherein said wear retarding means alsoincludes a hardened surface on each matrix segment defining said matrixsegment second seating surface.

3. The matrix assembly of claim 2 wherein each guide pin is guidinglyseated in a hardened guide sleeve insert carried by a respective matrixsegment.

4. The matrix assembly of claim ll wherein each guide pin is guidinglyseated in a hardened guide sleeve insert carried by a respective matrixsegment.

5. The matrix assembly of claim 4 wherein each guide pin has a stemportion and an enlarged head, said guide sleeve insert has a bodyportion defining a first guide surface and an apertured base defining asecond guide surface, and said first guide surface engaging said guidepin head and said second guide surface engaging said guide pin stem.

6. The matrix assembly of claim 5 wherein each guide pin carries acompression spring engaging said base of the respective guide sleeve andconstantly urging the respective matrix segment to an unseated position.

1. A matrix assembly for use in treading tires, said matrix assemblycomprising cooperating axially separable matrix shell halves, a matrixhalf carried by each matrix shell half, said matrix assembly having anaxis about which said matrix shell halves and said matrix halves aregenerally centered, each matrix half and its respective matrix shellhalf having first cooperating seating surfaces engageable in a planeextending generally transverse to said axis and second cooperatingseating surfaces extending generally circumferentially around said axisand disposed at a converging angle To said axis, each matrix half beingformed of a plurality of segments separately movable within and relativeto the respective matrix shell half in a combined axial andcircumferential direction from its seated position to a matrix expandingposition for the release of a treaded tire and the reception of a tireto be treaded, a pair of guide pins carried by each matrix shell halfmounting each respective matrix segment for guided retained movementbetween said seated position and said matrix expanding position, saidmatrix segments being formed of a relatively soft heat conducting metal,and wear retarding means for retarding wearing of said matrix segmentsduring the movement of said matrix segments, said wear retarding meansincluding said guide pins of each matrix segment being parallel andlying in a plane disposed at an angle to said axis generally equal tobut slightly less than said angle of said second seating surfaceswhereby as said matrix segments move to separate said first seatingsurfaces said matrix segment second seating surfaces movecircumferentially inwardly away from the respective matrix shell halfsecond seating surface and thereby prevent wearing of said secondseating surfaces.
 2. The matrix assembly of claim 1 wherein said wearretarding means also includes a hardened surface on each matrix segmentdefining said matrix segment second seating surface.
 3. The matrixassembly of claim 2 wherein each guide pin is guidingly seated in ahardened guide sleeve insert carried by a respective matrix segment. 4.The matrix assembly of claim 1 wherein each guide pin is guidinglyseated in a hardened guide sleeve insert carried by a respective matrixsegment.
 5. The matrix assembly of claim 4 wherein each guide pin has astem portion and an enlarged head, said guide sleeve insert has a bodyportion defining a first guide surface and an apertured base defining asecond guide surface, and said first guide surface engaging said guidepin head and said second guide surface engaging said guide pin stem. 6.The matrix assembly of claim 5 wherein each guide pin carries acompression spring engaging said base of the respective guide sleeve andconstantly urging the respective matrix segment to an unseated position.